1. Technical Field
The present invention relates to an image photographing device having a function for compensating hand vibration, and more particularly, to an image photographing device having a function for compensating hand vibration capable of minimizing deformations of a suspension wire caused due to an external impact by changing a shape of the suspension wire and a supporting structure supporting an optical unit.
2. Description of the Related Art
Recently, the use of a subminiature camera module for a mobile device has been increasingly expanded for mobile devices such as mobile phones, notebooks, tablet PCs, or the like. The subminiature camera used for the mobile devices has also required high pixels of five million pixels or more and a high function such as a zoom function, an auto focus (AF), or the like, according to customer demands.
Generally, the camera module used for the mobile devices may be configured to include an optical system including a lens, a lens driver moving the optical system to an optical axis direction to control a focus, and an image sensor photographing light input through the optical system to convert it into image signals.
As the camera module configured as described above is implemented as high pixels and high functions, the size of a pixel is small and the number of components through which light passes are increased, such that the light receiving sensitivity photographed by the image sensor may be sensitive and the focus of an image photographed by the image sensor become deviated even in slight hand vibrations at the instant when the shutter of the camera or the mobile device is operated, thereby deteriorating the image quality and obtaining blur photographs.
In order to prevent the deterioration in image quality due to hand vibration, as light passing through the lens of the optical system is generated by being deviated from the optical axis of the lens, the optical axis of the lens coincides with an incident path of light by moving the lens in a direction vertical to the optical axis or the optical axis coincides with the incident path of light received in the optical axis and the image sensor by moving the image sensor in a direction vertical to the optical axis, thereby compensating for the hand vibration.
That is, a relative displacement is assigned to the lens or the image sensor in a direction vertical to each optical axis, thereby compensating the hand vibration.
As described above, the method for compensating hand vibration by assigning the relative displacement to the lens or the image sensor generally installs a biaxial guide supporting the lens in a T-letter shape or an L-letter shape to move the lens in a relative direction of the driving displacement caused by the hand vibration while driving the lens in a direction vertical to the optical axis along the biaxial guide, thereby compensating the hand vibration.
In this case, when the lens moves along the biaxial guide, there are problems in that the compensation performance may be degraded due to the friction between the biaxial guide and the lens and noise or foreign materials may occur due to the friction with other component members at the time of driving the biaxial guide and the lens or the biaxial guide.
Further, since the biaxial guide supports the periphery of the lens, there is an advantage in that the size of the camera module may be increased by a space in which the biaxial guide is installed.
Meanwhile, in order to reduce the noise or the foreign materials, a method of driving the lens in a direction vertical to the optical axis in a floated state while the optical unit is supported by the suspension wire is provided. The optical unit moves in the relative direction of the driving displacement generated by the hand vibration due to the electromagnetic force in the state in which the optical unit is supported to the suspension wire, thereby compensating for the hand vibration.
The device for compensating the hand vibration according to the above-mentioned method does not cause the operation noise by not causing the friction between the optical unit and other components and can minimize the degradation in performance by not causing the foreign materials due to the friction.
However, when the external impact such as dropping is applied to the mobile device, the compression stress is applied to the suspension wired supporting the optical unit and when the compression stress is out of the unique breakdown stress of the wire, the wire is subjected to deformations, such as bending, rupturing, etc.
That is, when one or more shaft of the suspension wire supporting the optical unit is deformed, there are problem in that the function for compensating hand vibration is degraded or when the wire is ruptured, the optical unit may be inclined.
In order to prevent these problems, the breakdown stress may be increased by making the diameter of the suspension wire large. However, when the diameter of the suspension wire is large, the spring rigidity is increased in a direction orthogonal to the optical axis to degrade the driving performance for compensating the hand vibration, and the size of the driving member may be increased and the overall size of the photographing device having the function for compensating the hand vibration may be increased accordingly.